The present invention relates to a method and apparatus for examining a body by means of penetrating radiation. The invention is particularly useful in making medical examinations of a patient's body by X-rays, and is therefore described below with respect to such application, but it will be appreciated that the invention, or features thereof, could also be advantageously used in other applications, such as in medical examination procedures utilizing gamma rays, or in non-destructive industrial testing by X-rays or other penetrating radiation.
As distinguished from tomographic examinations, wherein a plurality of individual planar slices or sections of the examined body are imaged, the present invention is more particularly useful in single-view "full-body" examinations wherein the complete three-dimensional body, or a portion thereof, is imaged. In such "full-body" examinations, the complete three-dimensional body, or the portion thereof under examination, is exposed to the radiation (e.g., X-rays) projected from a source through the body onto a two-dimensional radiation-sensitive surface to produce a two-dimensional radiation pattern. Such a pattern is constituted of a plurality of picture elements, each of which is dependent on the attenuation suffered by the radiation traversing its respective substantially linear ray path through the examined body, from the radiation source to the point of impingement on the radiation-sensitive surface.
In using such single-view "full-body" X-ray imaging procedures for making medical examinations, it is highly desirable to maximize both the resolution and the stopping power of the radiation-sensitive surface. High resolution provides high definition of the image, thereby enabling the details to be better discerned, and high stopping power permits a larger proportion of the radiation passing through the object to be used, thereby minimizing the dosage required to be applied to the patient. Photographic film has been commonly used as the radiation-sensitive surface, but film has the disadvantages of poorly showing different densities and having very low stopping power. Because of these disadvantages, other detectors such as scintillating crystals, together with image-intensifier tubes and/or photographic film, have become more widely used as the radiation-sensitive surface. The stopping power of scintillating crystals is higher than film and increases with its thickness, but the resolution decreases with thickness. As a result, when a system is designed with thicker crystals in order to increase the stopping power and thereby to minimize the dosage to the patient, the resolution of the produced image suffers. This limits the extent to which the thickness, and thereby the stopping power, of the crystals can be increased.
An object of the present invention is to provide a method and apparatus for examining a body having advantages in the above respects. More particularly, an object of the present invention is to provide an examining method and apparatus in which the resolution of the produced image may be very substantially enhanced, thereby permitting the use of scintillating crystals having high stopping power so that both good resolution of the image and low dosage to the patient are more easily obtainable.